The present disclosure relates to rearview mirrors for motor vehicles and more specifically to an external fold rearview mirror assembly for motor vehicles.
The external fold rearview mirror assembly comprises a mirror head that can be rotated by means of a motor component between a mirror operative condition (driving position) and a mirror folded condition (parking position), and vice versa. The present mirror assembly can be also rotated manually from the mirror operative condition to the mirror folded condition if necessary.
Many current motor vehicles are currently fitted with mirror assemblies comprising a mirror head that can be driven in rotation by means of a motor component. The mirror head can be rotated by the motor component about a substantially vertical pivot axis for being arranged in a mirror operative condition (driving position) or in a mirror folded condition (parking position).
Locking means are provided for holding the mirror head in said driving and parking positions. The locking means may be for example a detent mechanism comprising detent elements formed in the mirror head and in a base member, respectively. The base member is adapted to be attached to the motor vehicle and, in use, the mirror head can be rotated by the motor component relative to the base member.
Although mirror assemblies actuated by a motor component may be efficient and comfortable for the user, in case of failure of the motor component it may be difficult to manually release the mirror head from the above mentioned locking means in order to rotate it into a different mirror position.
In an attempt to mitigate such disadvantage in prior art mirror assemblies actuated by means of a motor component, drive means are provided including clutch means. The clutch means are capable of disconnecting the motor component from the mirror head in some specific cases so that the mirror head can be rotated manually by the user.
Document EP2439106 discloses a rear view mirror assembly provided with drive means including a clutch member. The clutch member is axially movable from an engaged position restraining relative rotation to a mirror base and a disengaged position where only a frictional engagement restrains relative rotation between the clutch member and the mirror base by a non-back drivable electric drive train.
In U.S. Pat. No. 8,366,284 a rearview mirror assembly is disclosed comprising drive means provided with a clutch mechanism that connects a drive train to a base when the drive train is driving and disconnects the drive train from the base when the drive train is not driving.
However, when the mirror head has to be rotated manually by the user to the mirror operative condition (driving position) the gear wheel assembly in the prior art known solutions is not capable of allowing the user to arrange the mirror head in a final operative condition suitable for driving. This is because the detent mechanism does not provide accurate preset angular positions for the mirror head when being opened manually into the mirror operative condition (driving position). In such case, if the mirror head is forced to be arranged in an intermediate, accurate angular position suitable for driving, the mirror head becomes arranged in an unstable condition on the base member.
Such unstable angular position of the mirror head occurs since the intermediate angular position of the mirror head usually involves that the detent elements of the mirror head are arranged onto those of the base member. In this condition, all teeth are allowed to slide to each other while the vehicle is running, that is, no meshing occurs. Consequently, the mirror head is likely to be rotated back to a more stable angular position of the mirror head but probably not being the most appropriate for driving.